Add default value to display string

[anandtiwary]

Description

Please include a summary of the change, motivation and context.
feat: Add default value to display string

Testing

Please describe the tests that you ran to verify your changes. Please summarize what did you test and what needs to be tested e.g. deployed and tested helm chart locally.

Checklist:

• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• Any dependent changes have been merged and published in downstream modules

Documentation

Make sure that you have documented corresponding changes in this repository or hypertrace docs repo if required.

[codecov]

Codecov Report

Merging #766 (1b475fd) into main (41a3f03) will increase coverage by 0.00%.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##             main     #766   +/-   ##
=======================================
  Coverage   85.35%   85.35%           
=======================================
  Files         788      788           
  Lines       16128    16130    +2     
  Branches     2055     2058    +3     
=======================================
+ Hits        13766    13768    +2     
  Misses       2331     2331           
  Partials       31       31           

Impacted Files	Coverage Δ
...utilities/formatters/string/display-string.pipe.ts	100.00% <100.00%> (ø)
...rc/utilities/formatters/string/string-formatter.ts	100.00% <100.00%> (ø)

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[github-actions]

Unit Test Results

    4 files  ±0  247 suites  ±0   14m 25s ⏱️ - 1m 23s
885 tests +1  885 ✔️ +1  0 💤 ±0  0 ❌ ±0 
891 runs  +1  891 ✔️ +1  0 💤 ±0  0 ❌ ±0 

Results for commit ea6986c. ± Comparison against base commit 41a3f03.